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定理设二面角α-l-β的度数为θ(θ<π/2),α内的多边形A1,A2,A3,…An在β内的射影为A′1,A′2,A′3,…A′n,那么例1 三棱锥V-ABC的各个面的面积分别为S_VAB=3,S_VBC=4,S_VAC=5,S_ABC=6,且各侧面与底面所成的二面角相等,则这个二面角为( )
The theorem sets the dihedral angle α-l-β to θ(θ<π/2). The projections of the polygons A1, A2, A3,... An in α are A′1, A′2, A′ in β. 3,...A′n, then the area of each face of the trigonal pyramid V-ABC of Example 1 is S_VAB=3, S_VBC=4, S_VAC=5, S_ABC=6, and the dihedral angle formed by each side surface and the bottom surface is equal. , then this dihedral angle is ()